The present invention relates to manufacturing yarn filaments of varying denier and, more particularly, to an apparatus for manufacturing filaments exhibiting random variations in the denier along the length thereof.
Prior art abounds with apparatuses which are designed to draw fibers (filaments) with their primary object being to obtain a product which has a constant denier (fixed diameter) along its entire length. Generally speaking, it has been undesirable to obtain variations in filament denier. These variations cause dye to be absorbed unevenly, thereby causing variations in the final cloth fabricated with this type of yarn filament. Typical examples of prior art directed to the drawing of filaments which attempt to maintain a constant denier are listed below:
______________________________________ U.S. Pat. No. Invention Date Inventor ______________________________________ 3,978,192 August 31, 1976 Sussman 3,780,516 December 25, 1973 Kimbrell 3,623,311 November 30, 1971 Berger, Jr. 3,622,660 November 23, 1971 Ecker, et al. 3,558,767 January 26, 1971 Gopez, Jr. 2,289,232 July 7, 1942 Babcock ______________________________________
The above patents describe apparatuses and methods which include the use of heat and/or different mechanical techniques which attempt to maintain a constant denier. However, we are aware of only two patents which attempt to create a variable denier yarn. The first of which is U.S. Pat. No. 3,561,045 issued to Heffernan on Feb. 9, 1971. The Heffernan patent uses a draw roll which is provided with a matte circumferential band and a mirror-finish circumferential band on a cylindrical surface cooperating with a separator roller which has a matte cylindrical surface. A cam is provided between the feed roll and the draw roll to deflect the filament between the two bands in a predetermined manner related to the shape of the cam. Thus, the denier of the filament is varied in a prescribed predetermined manner directly related to the shape of the deflecting cam.
U.S. Pat. No. 3,323,165 to Mottern, et al, issued June 6, 1967, relates to an apparatus providing variable denier yarn. This particular apparatus uses a radiant heat means intermittently applied proximate the filament being drawn at a point between the feed roll and the draw roll. A variation in the denier of the filament or yarn is directly related to the relative position of the radiant heat means to the filament being drawn and is cycled in a prescribed manner. The drawing technique is similar to that shown in the prior art.
A new development in the yarn industry, in recent years, has been the use of flat yarn raw material in the form of a partially oriented yarn. By definition, this means that the yarn has not been fully drawn or oriented. This yarn is completely drawn in a tandem continuous step as described in the prior art. However, as shown in the prior art, since the polymer does not stay in the fully drawn state for more than a few seconds before a new texturized configuration is further imposed upon it, the hydrogen bonds between the molecules have not been established in the fully drawn condition, and the yarn more easily assumes and retains the textured condition. Thus, the use of partially oriented yarns allows faster processing, more effective heat setting, less degradation and improved texture. The use of the partially oriented yarn in carpets requires that they be subjected to very critical quality control standards, since the pile yarn in the carpet is a visible warp yarn. Also, pile height causes a foreshortening of the yarn to the viewer. Using this type of yarn for carpets allows very critical visual comparison of the yarns and very small optical differences are clearly visible as lengthwise streaks in the carpet.
Thus, if we assemble sufficient partially oriented yarns to meet the total carpet denier requirements and then draw and texturize the yarn bundle, very critical quality control would be required to assure that yarns from different manufacturing equipment do not cause streaks in the carpet.
Normally, the undrawn yarn is passed between two sets of yarn gripping rollers, the second set running faster than the first. Thus, the yarn is extended (drawn) by the difference in roller speeds. This technique is known in the prior art and is generally acceptable for manufacturing yarn and filaments for general use. However, this invention relates to manufacturing yarns with varying draw ratios (denier) along the length of the yarn. A number of these yarns will then be assembled, and since each yarn will have different draw ratios along its length and other yarns will have the same variance, but not at exactly the same values, the composite yarn will have a wide spectrum of draw ratios. This will give a differential dye take-up in the polyester element and hence, the composite yarn will dye to a heather mixture of different depths. But more importantly, all yarns produced on different machinery will have a sufficiently wide spectrum so that small variations and draw ratios caused by variances in manufacturing spindles will fall inside the overall spectrum.
The present invention overcomes the shortcomings known in the prior art and discloses a mechanism which is less costly than those known and readily provides yarn with a variable drawn (denier). The present invention utilizes electrically activated means (electromechanical) for providing tension in a random manner for obtaining variable denier yarn filaments. The tension applied to the filament is made proportional to the voltage appearing on the tension applying apparatus. By varying several parameters, a multiplicity of draw ratios can be obtained.